We have observed during numerous experiments involving stabilization of images on one or both retinas that static depth or motion-in-deth perception continues even during image disappearance. Based upon these and other observations, we have hypothesized two retinal image processing mechanisms. The first mechanism subserves form perception and requires movement of the retinal image, either through eye movements or movement of the imaged object. The second mechanism continues to function in the absence or retinal image motion, and is the mechanism that we think produces static and dynamic depth. Our objective is to use a selectively stabilized image technique, to examine whether there are in fact two retinal image processing mechanisms of this type and whether interactions between them could account for such phenomena as binocular suppression, ocular dominance, binocular rivalry, and the inhibition of depth perception by form perception. We will present observers with luminance sine-wave and square-wave gratins of varius spatial frequencies that can be stabilized or accurately moved on either retina and that can be varied in contrast. Contrast sensitivity functions for the perception of static depth and motion-in-depth will be measured under two sets of conditions: one eliminates inputs to the form perception mechanism (in one or both eyes), and the other does not. A comparison between the results obtained under these two conditions should enable us to decide whether the retinal image processing underlying form perception is necessary for static depth or motion-in-depth perception, binocular rivalry, or ocular dominance. A related series of experiments will be conducted in which slective image stabilization will enable us to isolate vergence inputs from retinal disparity inputs to stereopsis. These experiments should provide basic information about the influence of normal and abnormal retinal image motions on form and depth perception.